When using an electronic device having a battery, it is often advantageous to know how much charge remains in the battery. In the past, batteries were manufactured without a way of knowing how much charge remained in them, which presented several problems. Some of the problems encountered included, having to manually “test” batteries by connecting them to an electronic device to determine if they had any charge remaining (and even then how much charge they contained was usually unknowable), placing two or more batteries of different charge levels in the same device and a battery having a lower amount of charge draining charge from a battery having a higher amount of charge, and a battery running out of charge at an inconvenient time and/or location.
To overcome some of the problems associated with not knowing how much charge remained in a battery, a battery state-of-charge indicator (SOCI) was developed and connected to batteries to continuously monitor and display the amount of charge remaining. These early SOCIs, however, began to monitor and display the amount of charge remaining at the point of manufacture. Thus, a battery employing an early SOCI had a decreased overall lifetime, because the SOCI consumed power for substantially the entire time from when it was connected to the battery until the battery was completely discharged. This problem was exacerbated when such a battery was shipped and/or stored for a significant period of time, because the SOCI would continue to consume power—and sometimes completely drain the battery—prior to the battery being used.
Subsequently, a battery having a SOCI which was initially turned off was developed. These SOCIs had a removable Mylar strip located between the positive and negative terminals of the battery and were activated when the Mylar strip was removed from the battery. Once activated, the SOCI monitored and displayed the amount of charge left in the battery. Though these SOCIs overcame the problem of decreasing the overall lifetime of the battery, they presented problems of their own.
For example, in SOCIs utilizing a Mylar strip, the Mylar strip often broke without being completely removed from between the battery terminals. This resulted in the SOCI not functioning properly or not functioning at all, even after multiple attempts to remove the Mylar strip. In addition, the Mylar strip was often confusingly similar to a second Mylar strip included in some batteries for activating a complete discharge device which caused batteries to completely discharge all charge in them. Therefore, there is a need for a battery with the capability of being manufactured, shipped and/or stored with a SOCI turned off so the overall lifetime of the battery is not decreased, and include a way to activate the SOCI in a relatively easy manner that does not pose a significant risk of prematurely discharging the battery.